ICES advice 2018

“Hake (Merluccius merluccius) in subareas 4, 6, and 7, and in divisions 3.a, 8.a–b, and 8.d, Northern stock (Greater North Sea, Celtic Seas, and the northern Bay of Biscay)”


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ICES advice on fishing opportunities

ICES advises that when the MSY approach is applied, catches in 2018 should be no more than 115 335 tonnes.


Stock development over time

The spawning-stock biomass (SSB) has increased significantly since 2006 and is well above historical estimates. Fishing mortality (F) has decreased significantly after 2005, and has been below FMSY since 2012. The recruitment (R) estimate for 2016 is above average

Figure 1 Hake in subareas 4, 6, and 7, and in divisions 3.a, 8.a–b, and 8.d, Northern stock. Summary of the stock assessment.Recruitment, F, and SSB plots show 95% confidence intervals (shaded area). Assumed recruitment values are unshaded.


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Stock and explotation status


State of the stock and fishery relative to reference points


Catch scenarios


Table 2 Hake in subareas 4, 6, and 7, and in divisions 3.a, 8.a–b, and 8.d, Northern stock. The basis for the catch scenarios. All weights are in tonnes.
Variable Value Source Notes
F (2017) 0.26 ICES (2017a) Mean F(2014–2016).
SSB (2018) 267673.00 ICES (2017a)
R (2017/2018) 335071.00 ICES (2017a) GM (1978–2014); in thousands.
Total catch (2017) 105223.00 ICES (2017a) Forecasted catch from the assessment model (based on F(2017) = Mean F(2014–2016) plus additional discards.
Wanted catch (2017) 93588.00 ICES (2017a) Based on average discard rates observed during 2014–2016.
Unwanted catch (2017) 11635.00 ICES (2017a) Based on average discard rates observed during 2014–2016.



Table 3 Hake in subareas 4, 6, and 7, and in divisions 3.a, 8.a–b, and 8.d, Northern stock. Annual catch options. All weights are in tonnes.


Total.catch..2018. Wanted.catch..2018. Unwanted.catch..2018. Ftotal..2018. Fwanted..2018. Funwanted..2018. SSB..2019. X..SSB.change X..Advice.change
ICES advice basis
MSY approach: FMSY 115335 104060 11275 0.280 0.233 0.047 295193 10% -7%
Other options
F = 0 0 0 0 0.000 0.000 0.000 401929 50% -100%
Fpa 211827 190172 21655 0.620 0.515 0.105 206120 -23% 71%
Flim 261716 234150 27566 0.870 0.723 0.147 160047 -40% 111%
SSB (2019) = Blim 383469 337722 45746 2.293 1.904 0.389 44975 -83% 210%
SSB (2019) = Bpa 395825 347392 48433 2.731 2.268 0.463 32001 -88% 220%
SSB (2019) = MSY Btrigger 395825 347392 48433 2.731 2.268 0.463 32001 -88% 220%
F = F2017 108119 97580 10540 0.259 0.215 0.044 301860 13% -13%
EU Recovery Plan^^ 104736 94539 10196 0.250 0.208 0.042 304987 14% -15%
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Basis F Catch 2018 SSB 2019
MSY approach: FMSY 0.280 115335 295193
F = 0 0.000 0 401929
Fpa 0.620 211827 206120
Flim 0.870 261716 160047
SSB (2019) = Blim 2.293 383469 44975
SSB (2019) = Bpa 2.731 395825 32001
SSB (2019) = MSY Btrigger 2.731 395825 32001
F = F2017 0.259 108119 301860
EU Recovery Plan^^ 0.250 104736 304987

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Basis of the advice



Table 4 Hake in subareas 4, 6, and 7, and in divisions 3.a, 8.a–b, and 8.d, Northern stock. The basis of the advice.
Advice basis MSY approach.
Management plan The current recovery plan (EU, 2004) is based on precautionary reference points that are no longer appropriate. ICES has not evaluated this plan.


#Quality of the assessment
***
The uncertainty in the assessment is relatively high, with large changes in biomass estimates in consecutive years. The model confidence intervals are an underestimate of uncertainty because they are narrower than interannual changes in estimates in consecutive years. There is a lack of tuning data for the earlier years of the assessment, for some areas outside of subareas 7 and 8, and for the larger individuals in the population. Given the expansion of the stock into northern areas (ICES, 2017b), there is a potential that not all catches are reported for this stock. Biological sampling from these areas is also limited. The data compilation of this stock is very complicated because it is exploited by several countries and the assessment model configuration is complex. In turn, the assessment model is very sensitive to the data and the settings used. Hence, it is extremely important for the quality of the assessment to have the complete data for all the countries on time and in the right format.

Reference Points



Herring in Subarea 4 and divisions 3.a and 7.d, autumn spawners. Reference points, values, and their technical basis.
Framework Reference.point Value Technical.basis Source
MSY approach MSY Btrigger 45000 Bpa ICES (2016a)
NA FMSY 0.28 Stochastic simulations on a segmented regression stock–recruitment relationship. ICES (2016a)
Precautionary approach Blim 32000 A low biomass which was followed by a quick recovery. ICES (2016b)
NA Bpa 45000 1.4 × Blim ICES (2016b)
NA Flim 0.87 Fishing mortality resulting in a 5% probability of SSB falling below Blim. ICES(2016b)
NA Fpa 0.62 Flim/1.4 ICES(2016b)
Management plan SSBMGT No defined


Basis of the assessment



Herring in Subarea 4 and divisions 3.a and 7.d, autumn spawners. Basis of the assessment and advice
ICES.stock.data.category X1..ICES..2016c..
Assessment type Length-based model (SS3; ICES, 2017a) that uses landings and some discards in the model. Additional discards are then included to calculate a catch forecast.
Input data Commercial landings; four survey indices (EVHOE-WIBTS-Q4, SpPGFS-WIBTS-Q3, IGFS-WIBTS-Q4, and RESSGASC); maturity data: constant maturity (Martin, 1991); natural mortality: constant value (0.4).
Discards and bycatch Data series from most fleets are available; 75% of the observed discards are included in the assessment (ICES, 2017a). The discards not used in the assessment are used to top-up the catch advice.
Indicators None.
Other information Last benchmarked in 2014 WKSOUTH (ICES, 2014).
Working group Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE)

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